Determination of the 5-days BOD in only 48 h through an innovative ready-to-use analytical kit

A fast and reliable characterisation of biodegradable organic matter (BOM) is essential to ensure efficient pollution removal by wastewater treatment plants (WWTP) along with a necessary reduction of the environmental footprint resulting from treatment process operation (energy and raw material consumption, greenhouse gas emission). Biochemical Oxygen Demand (BOD) is a worldwide used indicator for assessing the BOM content of wastewater. The BOD measurement rests on a 100 years old analytical method which is became the reference today. As described by the ISO 5815 standard, BOD is determined after a 5-days incubation period at 20°C (BOD5). Useful for long-term controls, BOD5 cannot supply information fast enough for an efficient operation and optimisation of wastewater treatment processes. Moreover, the current reference method is very laborious, time-consuming and requires expensive and cumbersome equipment.

The AMS Envolure company (KPM Analytics group) has developed an innovative approach for fast and reliable BOD analysis. Sold as a 96-wells microplate kit, the Enverdi® method enables the determination of a BOD5 equivalent in only 48h at 30°C, by measuring the respirometric activity of bacteria through fluorimetric detection. This method has been successfully characterised and validated from 2014 to 2015, in collaboration with 2 end-user laboratories, according to the standards in force in the water quality field (NF T90-210 and ISO 11352). Moreover, several comparative studies towards the reference method were carried out from 2013 to 2016. Results from these comparative studies showed that the BOD5 values obtained from the Enverdi® kit and the reference method are statistically equivalent. No significant bias was found when considering nearly 393 municipal wastewater samples analysed by 6 end-user laboratories. Moreover, another research team found consistent BOD5 results when analysing pig slurry samples using the Enverdi® kit. Driven by these successful results, French government has published a derogatory decree in September 2017. This decree allows the end-user laboratories to experiment with the innovative method for 2 years in a well-defined and supervised regulatory framework.

The goal of this communication is to present in detail the latest results obtained with the Enverdi® kit for the BOD5 measurement in municipal wastewater. Additionally, we will present the regulatory experiment in progress in France since the last year regarding this application. We will also give an overview about additional applications of this innovative method as the measurement of very low BOD5 values in surface water, the biological fractionation of wastewater BOM for bioprocess operation modelling, or the detection of bacterial inhibitors in industrial effluents which are released in sewerage. Whatever the application, this innovative analytical kit shows numerous advantages compare to the corresponding reference methods as fast results, small-size equipment, user-friendliness, time- and cost savings.